1. Field of the Invention
The present invention relates to thermal modules and more particularly, to a high-performance thermal module directly press-forged from magnesium alloy and copper alloy. By means of press-forging, the cohesive energy density of the thermal module is high, and therefore the thermal module can be covered with a layer of metal coating by means of electroplating, improving beauty and quality.
2. Description of the Related Art
Despite of different design changes, conventional lighting fixtures use a lamp bulb or lamp tube to produce light. These conventional lighting fixtures have the common drawbacks of high consumption of electric energy and production of heat. The production of heat not only shortens the service life of the lighting fixture but also increases the ambient temperature. Further, a daylight lamp causes a flashing problem that is harmful to the eyes.
Nowadays, LEDs (light emitting diodes) have been intensively used in lighting fixtures to substitute for conventional lamp bulbs and tubes for the advantages of low power consumption and long service life. Further, because LEDs do not contain mercury, using LEDs for lighting fixture brings no harm to environment.
However, LEDs may be too dim in bright light situations because of its unidirectional lighting feature. Therefore, a LED lighting fixture has the drawback of limited angle of illumination. To overcome this problem, multiple LEDs may be arranged together and set in different angles. However, this arrangement greatly complicates the fabrication of the lighting fixture and will also increase the cost. Further, LEDs still produce heat during operation. The problem of heat will affect the brightness of LEDs and their service life.
Various thermal modules have been disclosed for use with LEDs to dissipate heat during operation of LEDs. Conventional thermal modules for this purpose are commonly extruded from aluminum alloy. Radiation fins may be provided to enhance heat dissipation. However, the heat dissipation effect of conventional thermal modules extruded from aluminum alloy is still not perfect. Currently, many thermal modules are known prepared from composition metal for use in electronic products. Taiwan Patent Publication Number 563846 is an exemplar. However, no composition metal type thermal module is known for use with a LED module.
Commercial composition type thermal modules commonly use aluminum for dissipating heat and copper for absorbing heat and transferring absorbed heat to aluminum for dissipation.
However, these composition type thermal modules are not ideal designs for the products that require EMI (electromagnetic interference) protection.
Further, following the market tendency toward light and small characteristics and the world's environmental protection trend, magnesium alloy has become the material market's favorite. Magnesium alloy has light characteristic. Further, magnesium alloy has excellent strength-to-weight ratio, high stiffness, excellent impact-resistance and wear-resistance capability, and magnetic wave absorbing and shock absorbing characteristics. Nowadays, magnesium alloy is intensively used in computer, communication and consumer electronic products.
There are manufacturers trying to use magnesium alloy for making thermal modules. However, magnesium alloy has the drawback of low flowability. Conventionally, casting and injection molding techniques are employed to fabric thermal modules from magnesium alloy. However, casting technique is not practical for making a magnesium alloy product having a thin wall. Making thermal modules from magnesium alloy by casting may encounter the problems of thermal cracking, oxidization, insufficient strength, deformation of the product upon ejection from the mold, and insufficient tightness that affect heat dissipation performance.
Further, unlike the application history of aluminum that is over several hundred years, magnesium is a new application material developed in last few decades. In the early stage, thermal module manufacturers are not familiar with the nature of magnesium. It is difficult and dangerous to process magnesium. It is almost impossible to make a composition type thermal module by using magnesium. Because magnesium is a hazardous metal tend to react with oxygen, molten magnesium will burn under an oxygen environment. When burning magnesium is covered with water, it will generate hydrogen and may explode. Therefore, it is difficult to fabricate a composition thermal module using magnesium.